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<h1>Neo4j Release Notes</h1>

<h3 id="2.0.3">Neo4j 2.0.3 (2014-04-30)</h3>

<p>Neo4j 2.0.3 is a maintenance release, with critical stability improvements.</p>

<p>Notably, this release addresses the following:</p>

<ul>
  <li>Fixes a concurrency issue in page caches that could occur during high load concurrent writes</li>
  <li>Resolves an occasional issue on shutdown whereby a cluster master could temporarily revert to a slave (Enterprise)</li>
  <li>Fixes a critical issue evaluating <code>ORDER BY & LIMIT</code> queries which would lead to missing results when duplicate sort keys were present (a 2.0.2-specific bug)</li>
</ul>

<p><strong>All Neo4j users are strongly recommended to upgrade to this release.</strong> Neo4j 2.0.3 does not require any store-level upgrades from the previous 2.0.0 release.</p>

<p class="footnote">For information about upgrading from Neo4j 1.9 or earlier, please see our <a href="/download/upgrade-faq">Upgrading to Neo4j 2.0 FAQ</a>.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.</p>


<h3 id="2.0.2">Neo4j 2.0.2 (2014-04-14)</h3>

<p>The 2.0.2 release of Neo4j is a maintenance release.</p>

<p>Notably, this release addresses the following:</p>

<ul>
<li>Adds new Cypher functions for type conversion (toInt, toFloat, toStr).</li>
<li>Resolves an issue with some specific Cypher queries that would never terminate.</li>
<li>The default value for the 'keep_logical_logs' setting has been changed to '7 days' (previously 'all'), to prevent issues with exahusting disk space in deployments where that setting has not been adjusted.</li>
<li>The online backup tool (Neo4j Enterprise) will now switch to a full backup when there are insufficient logical logs available to perform an incremental backup.</li>
<li>Corrected a memory leak in transaction management that could result in substantial degredation in performance and stability over time.</li>
<li>Resolves a deadlock that could occur during highly concurrent updates and querying.</li>
<li>Reduces verbosity of cluster transition logging (Neo4j Enterprise).</li>
<li>Resolves several cases where Neo4j instances could become unresponsive during role switching in a HA cluster (Neo4j Enterprise).</li>
<li>Corrects several issues with transaction application and recovery, that could result in slow recovery or failure to recover.</li>
<li>Resolves an issue where store migration (during upgrade) could fail to handle legacy indexes correctly.</li>
</ul>

<p class="footnote">For information about upgrading from Neo4j 1.9 or earlier, please see our <a href="/download/upgrade-faq">Upgrading to Neo4j 2.0 FAQ</a>.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.</p>

<h3 id="1.9.7">Neo4j 1.9.7 (2014-04-11)</h3>

<p>The 1.9.7 release of Neo4j is a maintenance release.</p>

<p>Notably, this release addresses:</p>

<ul>
  <li>The default value for the 'keep_logical_logs' setting has been changed to '7 days' (previously 'all'), to prevent issues with exahusting disk space in deployments where that setting has not been adjusted.</li>
  <li>The online backup tool (Neo4j Enterprise) will now switch to a full backup when there are insufficient logical logs available to perform an incremental backup.</li>
  <li>Corrected a memory leak in transaction management that could result in substantial degredation in performance and stability over time.</li>
  <li>Reduces verbosity of cluster transition logging (Neo4j Enterprise).</li>
  <li>Resolves several cases where Neo4j instances could become unresponsive during role switching in a HA cluster (Neo4j Enterprise).</li>
</ul>

<p><strong>Users of Neo4j 1.9 are strongly recommended to upgrade to this release.</strong> Neo4j 1.9.7 does not require any store-level upgrades.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release series, multiple behaviours and features of Neo4j have been declared as deprecated, in order to help users prepare for the removal of these in Neo4j 2.0. A <a href="http://docs.neo4j.org/chunked/1.9.7/deprecations.html"> list of deprecations</a> can be found in the Neo4j manual.</p>

<h3 id="2.0.1">Neo4j 2.0.1 (2014-02-04)</h3>

<p>The 2.0.1 release of Neo4j is a maintenance release, with signficant
stability and performance improvements.</p>

<p>Notably, this release addresses the following:</p>

<ul>
  <li>Improvements to propagation of updates around a HA cluster</li>
  <li>Improvements in stability when instances join, leave or fail in a HA cluster</li>
  <li>Addresses performance issues when creating unique constraints</li>
  <li>Resolves an issue with lost transactions in certain error cases</li>
  <li>Resolves an issue in Cypher, whereby MERGE could not be used within a FOREACH clause</li>
  <li>Adds Cypher support for double literals in exponent form</li>
  <li>Adds Cypher support for UTF-8 characters in identifiers</li>
  <li>Improves Cypher compile time type inference and resolves several type related issues</li>
  <li>Addresses several index lookup issues in Cypher, relating to the use of AND and NOT expressions</li>
</ul>

<p><strong>All Neo4j users are strongly recommended to upgrade to this release.</strong> Neo4j 2.0.1 does not require any store-level upgrades from the previous 2.0.0 release.</p>

<p class="footnote">For information about upgrading from Neo4j 1.9 or earlier, please see our <a href="/download/upgrade-faq">Upgrading to Neo4j 2.0 FAQ</a>.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.</p>

<h3 id="1.9.6">Neo4j 1.9.6 (2014-02-03)</h3>

<p>The 1.9.6 release of Neo4j is a maintenance release.</p>

<p>Notably, this release addresses:</p>

<ul>
  <li>A critical concurrency issue in the Cypher query language, that could lead to incorrect query results</li>
  <li>Improvements to propagation of updates around a HA cluster</li>
  <li>Improvements in stability when instances join, leave or fail in a HA cluster</li>
</ul>

<p><strong>Users of Neo4j 1.9 are strongly recommended to upgrade to this release.</strong>
    Neo4j 1.9.6 does not require any store-level upgrades.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release series, multiple behaviours and features of Neo4j have been declared as deprecated,
    in order to help users prepare for the removal of these in the next major Neo4j release.
    A <a href="http://docs.neo4j.org/chunked/1.9.3/deprecations.html"> list of deprecations</a> can be found in the Neo4j manual.</p>

<h3 id="2.0.0">Neo4j 2.0 (2013-12-11)</h3>

<p>Neo4j 2.0 is a major release which introduces significant changes to the Property Graph model,
    Cypher query language, and the user experience.</p>

<p>Notably, this release introduces:</p>

<ul>
  <li>Node labels &mdash; for marking nodes as members of a named group</li>
  <li>Cypher enhancements &mdash; new clauses, new functions, improved syntax</li>
  <li>Neo4j Browser &mdash; a new developer-focused user interface</li>
</ul>

<p><strong>Because of the significant changes, current users are cautioned to migrate to this release carefully.</strong>
    We recommend verifying the syntax and validating all responses from your Cypher scripts, REST calls, and Java code 
    before upgrading any production system. Upgrading to Neo4j 2.0.0 can not be reversed.</p>

<p>For information about upgrading, please see our <a href="/download/upgrade-faq">Upgrading to Neo4j 2.0 FAQ</a>.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.</p>

<p class="footnote"><strong>Note: </strong>All features marked as deprecated in the Neo4j 1.9 release series have been removed.
    Please see the <a href="http://docs.neo4j.org/chunked/1.9.5/deprecations.html"> list of deprecations</a> for any previous release in the Neo4j manual.</p>

<h3 id="1.9.5">Neo4j 1.9.5 (2013-11-11)</h3>

<p>The 1.9.5 release of Neo4j is a maintenance release that addresses several
    critical issues affecting HA cluster deployment and stability.</p>

<p>Notably, this release addresses:</p>

<ul>
  <li>Improvement to handling DNS hostnames, rather than IP addresses, in configuration</li>
  <li>Resolved several issues that could destabilise a HA cluster during failover and master election</li>
  <li>Improved shutdown of the database to ensure running transactions are given time to complete</li>
  <li>Improved delivery and processing of status messages within a HA cluster</li>
  <li>Resolved several concurrency issues in the database kernel, that could result in deadlocks or other failures</li>
  <li>Various performance improvements to traversals and graph algorithms</li>
</ul>

<p><strong>All Neo4j users are strongly recommended to upgrade to this release.</strong>
    Neo4j 1.9.5 does not require any store-level upgrades.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release series, multiple behaviours and features of Neo4j have been declared as deprecated,
    in order to help users prepare for the removal of these in the next major Neo4j release.
    A <a href="http://docs.neo4j.org/chunked/1.9.3/deprecations.html"> list of deprecations</a> can be found in the Neo4j manual.</p>

<h3 id="1.9.4">Neo4j 1.9.4 (2013-09-19)</h3>

<p>The 1.9.4 release of Neo4j is a maintenance release, introducing a new distribution of Neo4j Community Edition
    specifically for the Windows operating system (both 32 and 64 bit variants). This new distribution contains a native
    installer and a graphical user interface for managing Neo4j Server.</p>

<p>Neo4j 1.9.4 also contains minor improvements to logging and and monitoring services.</p>

<p><strong>Users of Neo4j 1.9.2 or earlier are strongly encouraged to upgrade to this release</strong> (there are no
    critical fixes requiring users of Neo4j 1.9.3 to upgrade). Neo4j 1.9.4 does not require any store-level upgrades.
</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within
    the distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release series, multiple behaviours and features of Neo4j have been
    declared as deprecated, in order to help users prepare for the removal of these in the next major Neo4j release. A
    <a href="http://docs.neo4j.org/chunked/1.9.4/deprecations.html"> list of deprecations</a> can be found in the Neo4j
    manual.</p>

<p class="footnote">Windows is a registered trademark of Microsoft Corporation in the United States and other
    countries.</p>

<h3 id="1.9.3">Neo4j 1.9.3 (2013-08-30)</h3>

<p>The 1.9.3 release of Neo4j is a maintenance release that addresses several
    critical issues, especially in high load clustered deployments.</p>

<p>In particular this release addresses:</p>

<ul>
    <li>Improvements to logging of HA clustering events</li>
    <li>Resolves an infrequent exception when iterating over the relationships of some nodes</li>
    <li>Resolved rare concurrency issue in persistence window pools</li>
    <li>Improvements to reduce disk space and memory consumption by indexes</li>
    <li>Corrects several race conditions in the High-Availability (HA) protocol and in the distribution of transactions
        in a clustered environment
    </li>
    <li>Introduces an additional configuration option to control logical log rotation (logical_log_rotation_threshold)
    </li>
    <li>Resolves an issue with rolling upgrade support (rolling upgrade to 1.9.3 is supported from all previous 1.9 and
        1.8 releases)
    </li>
</ul>

<p><strong>All 1.9 users are recommended to upgrade to this release.</strong> Neo4j 1.9.3 does not require any
    store-level upgrades.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within
    the distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release series, multiple behaviours and features of Neo4j have been
    declared as deprecated,
    in order to help users prepare for the removal of these in the next major Neo4j release. A <a
            href="http://docs.neo4j.org/chunked/1.9.3/deprecations.html"> list of deprecations</a> can be found in the
    Neo4j manual.</p>

<h3 id="1.9.2">Neo4j 1.9.2 (2013-07-16)</h3>

<p>The 1.9.2 release of Neo4j is a maintenance release that corrects a serious issue concurrency issue introduced in
    Neo4j 1.9.1,
    and resolves some other critical issues when reading from the underlying store.</p>

<p>In particular this release addresses:</p>

<ul>
    <li>Fixes a concurrency issue when generating JSON payload in response to requests over the REST API</li>
    <li>Resolves an issue where relationships with very high IDs could be ignored during reading</li>
    <li>Improves performance when flushing changes to disk on windows systems</li>
    <li>Resolves an isolation issue when using the Cypher query language</li>
    <li>Corrects the setting of Content-Type and Content-Encoding headers in REST API responses</li>
</ul>

<p><strong>All 1.9 users are recommended to upgrade to this release.</strong> Neo4j 1.9.2 does
    not require any store-level upgrades.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within
    the distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release series, multiple behaviours and features of Neo4j have been
    declared as deprecated, in order to help users prepare for the removal of
    these in the next major Neo4j release. A <a href="http://docs.neo4j.org/chunked/1.9.2/deprecations.html">
        list of deprecations</a> can be found in the Neo4j manual.</p>

<h3 id="1.9.1">Neo4j 1.9.1 (2013-06-24)</h3>

<p>The 1.9.1 release of Neo4j is a maintenance release that brings more safety
    features into high-availability cluster deployments, general bug fixes and a small
    number of API enhancements.</p>

<p>In particular this release addresses:</p>

<ul>
    <li>Fixed race condition that could have lead to duplication in the getSingleRelationship()
        in the Core API.
    </li>
    <li>Reduces churn in the resource pool for channels and memory in a clustered environment.</li>
    <li>Individual pages in <a
            href="http://docs.neo4j.org/chunked/stable/rest-api-traverse.html#rest-api-creating-a-paged-traverser">paged
        traversals</a>
        through the <a href="http://docs.neo4j.org/chunked/stable/rest-api.html">REST API</a> can now be
        streamed like the other parts of the REST API, see <a
                href="http://docs.neo4j.org/chunked/stable/rest-api-streaming.html">the RESTstreaming docs</a>.
    </li>
    <li>SSL certificate chains are supported by the Neo4j server for secure interactions with the
        <a href="http://docs.neo4j.org/chunked/stable/rest-api.html">REST API</a>.
    </li>
</ul>

<p><strong>All 1.9 users are recommended to upgrade to this version.</strong> Neo4j 1.9.1 does
    not require any store-level upgrades.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within
    the distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release series, multiple behaviours and features of Neo4j have been
    declared as deprecated, in order to help users prepare for the removal of
    these in the next major Neo4j release. A <a href="http://docs.neo4j.org/chunked/1.9.2/deprecations.html">
        list of deprecations</a> can be found in the Neo4j manual.</p>


<h3 id="1.9">Neo4j 1.9 (2013-05-13)</h3>

<p>The 1.9 release of Neo4j builds upon the previous 1.8 releases and
    brings extensive improvements in stability and performance. In addition,
    <i>Neo4j 1.9 Enterprise</i> introduces auto-clustering support,
    with dramatically simplified configuration and deployment for high demand
    production use.</p>

<ul>
    <li>Support for <a href="http://docs.neo4j.org/chunked/1.9/ha.html">auto-clustering in
        <i>Neo4j Enterprise</i></a>, which replaces the previous Zookeeper
        based HA clustering, provides a streamlined deployment process and is
        much safer and more resilient in failure scenarios.
    </li>
    <li>New <a href="http://docs.neo4j.org/chunked/1.9/arbiter-instances.html">neo4j-arbiter</a>
        tool, which acts as a voting instance in a Neo4j cluster but does not
        keep a data store or handle transactions.
    </li>
    <li>Addition of <a href="http://docs.neo4j.org/chunked/1.9/query-function.html">
        string manipulation, timestamp and other functions</a> to the Cypher query language.
    </li>
    <li>Improvements to memory utilization, which reduces working memory requirements and
        improves overall performance.
    </li>
    <li>New <a href="http://docs.neo4j.org/chunked/1.9/ha-rest-info.html">REST endpoints for
        inspecting cluster status information</a> (master, slave, etc).
    </li>
    <li>Correction of several concurrency and performance issues.</li>
    <li>Improvements to <a href="http://docs.neo4j.org/chunked/1.9/operations-backup.html">
        Online Backup</a> in <i>Neo4j Enterprise</i>, including auto-detection of
        full vs incremental backup based on existing content at the backup location.
    </li>
    <li>Updates to Neo4j server webadmin, including welcome pages for new users.</li>
</ul>

<p><strong>It is recommended to upgrade all previous Neo4j installations to
    this release.</strong> Neo4j 1.9 does not require any explicit upgrade to
    persistent stores created using Neo4j 1.7 and 1.8 installations, however
    <i>current users of Neo4j Enterprise must consult the documentation and
        update the cluster configuration</i>. Please see the
    <a href="http://docs.neo4j.org/chunked/1.9/deployment.html">deployment</a>
    and <a href="http://docs.neo4j.org/chunked/1.9/upgrade-guide.html">cluster
        upgrade</a> sections of the neo4j manual for more detail. Also note that
    Neo4j 1.9 is tested and supported with
    <a href="http://www.oracle.com/technetwork/java/javase/downloads/index.html">Oracle
        JRE 7</a>. <i>Users of previous Java versions should upgrade to
        <a href="http://www.oracle.com/technetwork/java/javase/downloads/index.html">Oracle
            JRE 7</a> when deploying Neo4j 1.9.</i></p>

<p>For a full summary of changes in this release, please review the CHANGES.TXT file contained within the
    distribution.</p>

<p class="footnote">As part of the Neo4j 1.9 release, multiple behaviours and features of Neo4j have been
    declared as deprecated, in order to help users prepare for the removal of
    these in the next major Neo4j release. A <a href="http://docs.neo4j.org/chunked/1.9.2/deprecations.html">
        list of deprecations</a> can be found in the Neo4j manual.</p>

<hr/>
<h3 id="1.8.3">Neo4j 1.8.3</h3>

<p>The 1.8.3 release of Neo4j is a maintenance release that brings more safety
    features into high-availability cluster deployments, general bug fixes and a small
    number of API enhancements.</p>

<p>In particular this release addresses:</p>

<ul>
    <li>Ensure auto-indexes correctly expunge deleted nodes and relationsips.</li>
    <li>Fixed race condition that could have lead to duplication in the getSingleRelationship()
        in the Core API.
    </li>
    <li>Reduces churn in the resource pool for channels and memory in a clustered environment.</li>
    <li>Corrects an issue when supplying arrays as properties during unique node creation.</li>
</ul>

<p><strong>All 1.8 users are strongly recommended to upgrade to this version.</strong> Neo4j 1.8.3 does
    not require any store-level upgrades.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained
    within the distribution.</p>

<h3 id="1.8.2">Neo4j 1.8.2</h3>

<p>The 1.8.2 release of Neo4j is a service release and includes the following corrections and improvements:</p>

<ul>
    <li>Improvements to diagnostic logging and to the reliability of embedded APIs during instance fail-over
        (Neo4j Enterprise in HA configuration).
    </li>
    <li>Improvements to the database recovery process to avoid some scenarios that could cause the recovery
        after an unclean shutdown to fail.
    </li>
    <li>Correction of an isolation issue that could cause the failure of some traversals in the presence of
        concurrent write transactions.
    </li>
    <li>Allowing for a greater number of relationship types to be created within a single database. Neo4j now
        supports 65536 different relationship types.
    </li>
    <li>Improved store locking to prevent concurrent access of the store by multiple processes.</li>
    <li>Neo4j server will now use X-Forwarded-Host and X-Forwarded-Proto headers, if present, when generating
        the URIs contained in responses from the REST API.
    </li>
</ul>

<p><strong>It is recommended to upgrade all Neo4j 1.8.1 (and earlier) installations to this release, which is
    fully backward compatible</strong>. Please see the <a
        href="http://docs.neo4j.org/chunked/1.8.2/deployment.html">deployment section of the neo4j manual</a>
    for more detail.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within
    the
    distribution.</p>

<hr/>

<h3 id="neo4j-1.8.1">Neo4j 1.8.1</h3>

<p>The 1.8.1 release of Neo4j is a service release and includes the following corrections and improvements:</p>

<ul>
    <li>Correction of several errors in the parsing and evaluation of Cypher statements.</li>
    <li>Improvements in the memory footprint of most Cypher statements.</li>
    <li>Correction of an error in calculating shortest paths that could occur for some graph structures.</li>
    <li>Improvements in the diagnostic logging required for support provided by Neo Technology.</li>
</ul>

<p><strong>It is recommended to upgrade all Neo4j 1.8 (and earlier) installations to this release, which is
    fully
    backward compatible</strong>. Please see the <a href="http://docs.neo4j.org/chunked/1.8.1/deployment.html">deployment
    section of the neo4j manual</a> for more detail.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within
    the
    distribution.</p>

<hr/>

<h3 id="neo4j-1.8">Neo4j 1.8</h3>

<p>The 1.8 release of Neo4j provides extensive improvements in
    stability and performance. As an incremental service release, Neo4j 1.8 builds upon the previous 1.6 and 1.7
    releases and provides full backward compatibility.</p>

<p>This release includes the following corrections and improvements:</p>
<ul>
    <li>Correction of several concurrency issues affecting performance in multi-threaded configurations.</li>
    <li>Correction of several concurrency issues that infrequently affect consistency of persisted data.</li>
    <li>Optimization of high-availability (HA) protocols to increase write performance.</li>
    <li>Support for zero-downtime rolling upgrades in HA clusters.</li>
    <li>Improvements to transaction distribution in HA clusters, providing greater resistance to branching.</li>
    <li>Configurable rotation of logical logs.</li>
    <li>Support for streamed responses to REST API requests.</li>
    <li>Support for bi-directional traversals, branch state and path expanders in the traversal framework.</li>
    <li>Performance improvements to several graph algorithms.</li>
    <li>Support in the Cypher language for writing graph data and updating auto-indexes (manual indexes are not
        supported).
    </li>
    <li>Extensions to the Cypher language to allow the use of patterns as expressions and predicates.</li>
    <li>Correction of several issues in the Cypher parser when using collections and when aggregating.</li>
    <li>Improved error reporting in Cypher and more reliable statement parsing.</li>
    <li>Support for explicit transactions in neo4j-shell.</li>
</ul>

<p><strong>It is recommended to upgrade all previous Neo4j installations to this release.</strong> Neo4j 1.8
    does not require
    any explicit upgrade to persistent stores created using Neo4j 1.6 and 1.7 installations. Please see the
    <a href="http://docs.neo4j.org/chunked/1.8/deployment.html">deployment section of the neo4j manual</a> for
    more detail.</p>

<p class="footnote">For a full summary of changes in this release, please review the CHANGES.TXT file contained within
    the
    distribution.</p>
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